Drawing instrument



March 1 1927.

- T. F. MCCAFFERY, JR

DRAWING INSTRUMENT Filed oct. '2, 19.24

Patented Mar. 1, 1927.-

THOMAS I'. EUOAIIEBY, JB., 0F COLORADO SPRINGS, COLORADO.

DRAWING INSTRUMENT.

Application mea october 7, 1924. serial No. 742,202;

The device forming the subject matter of this application is a drafting tool combining, in a single instrument, a lplurality of scales, a'triangle, a protractor, andan eraser guard, and the invention aimsto provide novel means for protecting and 'sustaining the protractor. j n I t isv within the province of the disclosure to improve generally and to enhace l0 the utility of devices of that type to which the invention appertains.

Although a preferred form of the invention has been shown, it will be understood that'a mechanic, working within the' sco e of what is claimed, may make changes wi out departing from the spirit of the invention.

'In the drawings Figure l'is a plan; and Figure 2 is a sec- 10 tion on the line 2-2 ,of Figure 1.

The device vforming the subject matter of this application may be made out of any desire material, includes a frame 1 of approximately triangular outline, the frame having an opening 2. A semi-circular protractor 3 is joined at its ends to one si e member l4 of the frame 1, whereby said side member will form a base for the protractor. The other o side members 5 and 6 of the frame 1l constitute ards for the protractor 3.- -An arm 7 exten s from the intermediate 'ortion of the protractor 3 to the place o june ure between said other side members 5 and of the frame, and serves to hold the protractor 3 and the frame 1 against bending out ofl a common plane.

The side member 4 of the frame 1 has a projection 8, provided with an opening 9 which forms thecenter vpoint of the protractor v3, the protractor being graduated in any suitable way. In the present instance, but not of necessity, the protractor is graduated,l as shown at 10 in op osite directions, from 0 to 180. yThe arm has a slot 11, the axis of which coincides with the 90 mark of the rotractor 3,. the slot being beveled at its e ges 'so that an eraser may be operated conveniently in the slot.

I0 Scales 12 of any desired sort are located along the. outer edges of the members 4, 5 and 6 of the triang e or frame. The` memocated in the o ening 2 andis" bers 4, 5 and 6 of the triangle or frame are equipped with elongated openings 14, and there are scales 15 on the triangle, along both the inner and outer edgesof the openmgs 14. The members and 5 of the t'riangle or frame areA supplied with scales 16.

The .general construction of-the instrument is such that it combines `the advantages of a triangle, a plurality of rulers or scales, an eraser guard, and a 'protractor. If a straight edge is made to coincidewith the vertex of the angle formed by the outer edges of the parts 5 and 6 ofthe triangle, andr with the 90 mark of the protractor 3, a pencil line may be drawn through the slot 11. This operationmakes it unnecessary for the draftsman to use the center oint 9 in drawing the aforesaid line. oreover, the line can be drawn directly on the pa er, within the contour of the trian le, an it is unnecessary to. prick the pomt into the paper, at a int external to the triangle, remove the ytrlan'gle, draw the line through the prick point on the paper, and then reset the triangle with vthe center point 9 in pxroper position.

Having t us described the inventiom'what is claimed isz- In a device of the class described, a frame `of triangular outline, and having an opening the edges of which, throughout a maler portion of their length, are parallel to the outery edges of the frame, a semi-circular protractorY in the opening and 'oined at .its ends to one side member ofthe me whereby said side member will form a base forthe 1p )li'at-)ltlractor, the other side members of the e constituting guards for the protractor, and an arm extended from the intermediate portion of the protractor to the place of juncture between said other side members of the frame and serving to hold the protractor and the frame against bending out of a common plane, the arm having an elongated opening the prolonged axis of which passes through the external angle defined by the outer ed es of said other side members, and throng the 90 mark of the protractor.

In testimony that I claim the foregoing as my own, I have hereto aiiixedmy signature.

THOMAS F. MUCAFFERY, l JB. 

